Process of making a refastenable mechanical fastening system with substrate having protrusions

ABSTRACT

The invention is a refastenable mechanical fastening system, made of flee-formed prongs joined to an embossed or raised substrate. The prongs taper and are nonperpendicularly oriented relative to the plane of the substrate. Each prong has an engaging means projecting laterally from the periphery of the prong. The free formed prongs are manufactured by the process of depositing liquid material onto the embossed or raised portion of a moving substrate, stretching the liquid material in a direction parallel to the plane of the embossed or raised substrate and severing the stretched material to form the distal end and engaging means of the prong. The advantageous usage of the fastening system in an article of manufacture, such as a disposable absorbent garment, specifically a diaper, is also disclosed.

FIELD OF THE INVENTION

The present invention relates to refastenable mechanical fasteningsystems, more particularly to fastening systems having free formedprongs attached to the protruding portion of a substrate and the pressof manufacturing such fastening systems.

BACKGROUND OF THE INVENTION

Refastenable mechanical fastening systems are well known in art.Typically, such fastening systems involve two major components, a prongthat is joined to a substrate that engages with a complement secondcomponent,the receiving surface. A projection of the prong of thefastening system penetrates the receiving surface and either engages orintercepts strands or fibers of the receiving surface. The resultingmechanical interference and physical obstruction prevent removal of thefastening system from the receiving surface until the separation forcesexceed either the peel or shear strength of the fastening system.

Refastenable mechanical fastening systems have been disclosed by anumber of references. Examples include: U.S. Pat. No. 2,717,437, issuedSept. 13, 1955 to de Mestral; U.S. Pat. 3,009,5 issued Nov. 11, 1961 tode Mestral; U.S. Pat. No. 3,147,528, issued Sept. 8, 1964 to Erb; U.S.Pat. No. 3,594,863, issued Jul. 27, 1971 to Erb; U.S. Pat. No.3,708,833, issued Jan. 9, 1973 to Ribich et al.; U.S. Pat. No.3,943,981, issued Mar. 16, 1976 to De Brabandar; U.S. Pat. No.4,216,257, issued Aug. 5, 1980 to Schams et al.; U.S. Pat. No.4,307,493, issued Dec. 29, 1981 to Ochiai; U.S. Pat. No. 4,330,907,issued May 25, 1982 to Ochiai; U.S. Pat. No. 4,454,183, issued Jun. 12,1984 to Wollman; U.S. Pat. No. 4,463,486, issued Aug. 7, 1984 toMatsuda; U.S. Pat. No. 4,984,339, issued Jan. 15, 1991 to Provost etal.; U.S. Pat. No. 5,058,247 issued Oct. 22, 1991 to Thomas et al.; andU.S. Pat. No. 5,116,563 issued May 26, 1992 to Thomas et al. Anadditional reference of interest includes: European Pat. No. 276,970,filed Jan. 26, 1988, by the Procter & Gamble Company in the name ofScripps.

It is an object of the present invention to provide a free formedmechanical fastening system attached to a protrusion on the substratesurface, the prong is produced by a method of manufacture similar togravure printing. However, instead of utilizing an engraved print roll,a substrate having protrusions is used. It is also an object of thisinvention to provide a fastening system attached to protrusions on thesubstrate which have tapered prongs that do not perpendicularly projectfrom the associated substrate.

BRIEF SUMMARY OF THE INVENTION

The invention comprises a fastening system which is affixed toprotrusions on a substrate which attach to a complementary receivingsurface. The fastening system has at least one protrusion on thesubstrate surface and at least one free formed prong, attached to theprotrusion, comprising a base, shank and engaging means. The base of theprong is joined to the prong attachment surface of the protrusion of thesubstrate. The shank is contiguous with and projects outwardly from thebase. The engaging means is joined to the shank and projects laterallybeyond the periphery of the shank. The shank is nonperpendicularlyoriented relative to the plane of the substrate. The shank has a leadingedge and a trailing edge defining a leading angle and trailing anglerespectively. The leading angle and trailing angle are substantiallydifferent from each other, so that the sides of the shank arenonparallel.

The fastening system may be made according to the process comprising thesteps of heating a thermally sensitive material sufficiently to reduceits viscosity for processing, and preferably to at least its meltingpoint. A means to deposit discrete amounts of the heated material isprovided. The substrate having protrusions to which the material is tobe joined is transported in a first direction relative to the means fordepositing the material. The material is deposited upon the protrudingportions of the transported substrate in discrete amounts. The discreteamounts of material are then stretched in a direction having a componentgenerally parallel to the plane of the substrate and the stretchedmaterial is severed to form a distal end and engaging means.

An illustrative and suitable, but nonlimiting, use for the fasteningsystem produced by the process of the present invention is inconjunction with a disposable absorbent garment, such as a diaper. Thisexample of one usage of the present invention is more fully describedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

While the Specification concludes with claims particularly pointing outand distinctly claiming the invention, it is believed the invention willbe better understood from the following description taken in conjunctionwith the associated drawings in which like elements are described by thesame reference numeral and related elements are designated by adding oneor more prime symbols or incrementing the numeral by 100:

FIG. 1 is a perspective view of a single prong of the fastening systemof the present invention placed upon a substrate protrusion. Thesubstrate protrusion is an emboss.

FIG. 2 is a schematic side elevational view of a single prong of thefastening system shown in FIG. 1.

FIG. 3 is a schematic side elevational view similar to FIG. 2, however,the substrate protrusion is a raised area. The raised area comprises twoattachment surfaces; a prong attachment surface and a substrateattachment surface.

FIG. 4 is a schematic elevational view of a second embodiment having agenerally semispherically shaped engaging means placed upon an emboss.

FIG. 5 is a schematic side elevational view of one apparatus which canbe used to produce the fastening system of the present invention.

FIG. 6 is a perspective view of a fastening system of the presentinvention wherein the engaging means are oriented in substantiallyrandom directions and placed upon an emboss.

FIG. 7 is a schematic side elevational view of another apparatus whichcan be used to both emboss a suitable substrate and produce thefastening system of the present invention.

FIG. 8 is a perspective view of a disposable absorbent garment utilizingthe fastening system of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

By "protrusion", "protruding" or "protuberance" as used herein, means aportion of the substrate or an element affixed to the substrate surfacewhich is higher in relief from the plane of the surface of thesubstrate, and has a surface to which a prong can be joined.

By "prong attachment surface" as used herein, means that portion of aprotrusion or protuberance to which a prong will be joined.

The fastening system 20 of the present invention comprises at least oneprong 22, and preferably an array of prongs 22, joined to the protrudingportion 23 of a substrate 24 in a predetermined pattern. The prongs 22have a base 26, shank 28 and engaging means 30. The bases 26 of theprongs 22 contact and adhere to the prong attachment surface 25, of thesubstrate protrusions 23, and support the proximal ends of the shanks28. The shanks 28 project outwardly from the substrate protrusions 23.The shanks 28 terminate at a distal end which is joined to an engagingmeans 30. The engaging means 30 radially project laterally from theshanks 28 in one or more directions and may resemble a hook-shaped tine.As used herein, the term "lateral" means having a vector componentgenerally parallel to the plane of the prong attachment surface 25 atthe principal prong 22 under consideration. The projection of anengaging means 30 from the shank 28 periphery in a lateral directionallows the engaging means 30 to be, secured to a complementary receivingsurface (not shown). The engaging means 30 is joined to, and preferablycontiguous with, the distal end of the prong 22. It will be apparent theengaging means 30 may be joined to the prong 22 at a position betweenthe base 26 and the distal end of the shank 28.

An array of prongs 22 may be produced by any suitable method, includingmethods which yield a free formed prong 22 as described and claimedhereinbelow. As used herein, the term "free formed" means a structurewhich is not removed from a mold cavity or extrusion die in solid formor with a defined shape. The prongs 22 are deposited onto the prongattachment surface 25 of the substrate protrusions 23 of a noncontiguoussubstrate 24 in a molten, preferably liquid state and solidify, bycooling until rigid and preferably freezing, into the desired structureand shape as described hereinafter.

A free formed array of prongs 22 is preferably produced by amanufacturing process which is similar to that process commonly known asgravure printing. Using this process, a substrate 24 having protrusions23 is passed between the nip 70 of two generally cylindrical rolls, aprint roll 72 and a backing roll 74, as illustrated at FIG. 5. The rolls72 and 74 have generally parallel centerlines and are maintained suchthat at least roll 72 is in a contacting relationship with the prongattachment surface 25 of the protruding portions 23 of the substrate 24as it passe through the nip 70. One of the rolls, referred to as theprint roll 72, is smooth and is covered with a thin layer of thermallysensitive material. As the protruding portions 23 of the substrate 24passes through the nip 70 between the print roll 72 and the second roll,referred to as the backing roll 74, thermally sensitive material isdeposited upon the prong attachment surface 25 of the substrateprotrusions 23. The pattern of substrate protrusions 23 correspond tothe pattern of the prong array 22 which will be produced. During thisprocess the nip 70 should be fixed and open, having a gap sufficient toallow the pattern of substrate protrusions 23 to contact and appendadhesive material from the smooth print roll 72. Liquid, thermallysensitive material, preferably thermoplastic material, from which theprongs 22 are to be formed is supplied from a heated source, such as atrough 80. The thermally sensitive material is introduced onto thesmooth print roll 72 as it is rotated about its centerline. The smoothprint roll 72 with the thermally sensitive material spread upon itssurface contacts only the substrate protrusions 23, and preferably onlythe prong attachment surfaces 25. Therefore, preferably, deposit of thethermally sensitive material is made exclusively on the prong attachmentsurfaces 25 of the substrate protrusions 23.

As relative displacement between prong attachments surfaces 25 of theprotrusions 23 on the substrate 24 and rolls 72 and 74 continues, theprongs 22 are stretched with a lateral component, generally parallel tothe plane of the prong attachment surface 25, forming the shank 28 andthe engaging means 30. Finally, the moil of the prong 22 is severed fromthe engaging means 30 by a severing means 78. Due to the viscoelasticproperties of the thermoplastic, the prong 22 retracts under theinfluences of gravity and shrinkage which occurs during cooling. Theprong 22 then cools, and preferably freezes, into a solid structurehaving the engaging means 30 contiguous with the shank 28.

The fastening system 20 is secured to a complementary receiving surface.As used herein, the term "receiving surface" to which the engaging means30 of the fastening system 20 are secured refers to any plane or surfacehaving an exposed face with tightly spaced openings complementary to theengaging means 30 and defined by one or more strands or fibers or,alternatively, which exposed face is capable of localized elasticdeformation so that the engaging means 30 may become entrapped and notwithdrawn without interference. The openings or localized elasticdeformations allow for entry of the engaging means 30 into the plane ofthe receiving surface, while the strands (or nondeformed material) ofthe receiving surface interposed between the openings (or deformedareas) prevent withdrawal or release of the fastening system 20 untildesired by the user or either the peel or shear strength of thefastening system 20 is otherwise exceeded. The plane of the receivingsurface may be flat or curved.

A receiving surface having strands or fibers, is said to be"complementary" if the openings between strands or fibers are sized toallow at least one engaging means 30 to penetrate into the plane of thereceiving surface, and the strands are sized to be engaged orintercepted by the engaging means 30. A receiving surface which islocally deformable is said to be N "complementary" if at least oneengaging means 30 is able to cause a localized disturbance to the planeof the receiving surface, which disturbance resists removal orseparation of the fastening system 20 from the receiving surface.

Suitable receiving surfaces include reticulated foams, knitted fabrics,nonwoven materials, and stitchbonded loop materials, such as VELCRObrand loop materials sold by Velcro USA of Manchester, N.H. Aparticularly suitable receiving surface is stitchbonded fabric Number970026 sold by the Milliken Company of Spartanburg, S.C.

Referring back to FIGS. 2 and 3 to examine the components of thefastening system 20 in more detail, the substrate 24 of the fasteningsystem 20 should be strong enough to preclude tearing and separation ofindividual prongs 22. The substrate 24 should be a surface that iscapable of having additional material attached forming protrusions 23consisting of raised areas 21 as in FIG. 3. The raised areas 21 containtwo separate attachment surfaces; a prong attachment surface 25 to whichis joined the base of a free formed prong 22 forming a base-prongattachment surface interface, and a substrate attachment surface 27forming a protrusion-substrate interface. The substrate attachmentsurface 27 is sufficiently joined to the substrate 24 to avoidseparating from the substrate upon removal of the engaging means 30 fromthe complementary receiving surface.

Alternately, the substrate 24 should be sufficiently flexible andcapable of being stretched to form protrusions 23 which are embosses 19as in FIG. 2 The embosses 19, formed from the substrate 24 materialcontain a prong attachment surface 25 to which is joined the base of afree formed prong 22 creating a base-prong attachment surface interface.The prongs 22 will readily adhere and be capable of being joined to anarticle to be secured as desired by a user. As used herein the term"join" refers to the condition where a first member, or component, isaffixed, or connected to a second member or component, either directly;or indirectly, where the first member or component is affixed orconnected to an intermediate member, or component which in turn isaffixed, or connected, to the second member or component. Theassociation between the first member, or component, and the secondmember, or component, is intended to remain for the life of the article.The "substrate" is any exposed surface having one or more protuberances23 consisting of embossed 19 or raised areas 21 as illustrated in FIGS.2 and 3, having a prong attachment surface 25 to which one or moreprongs 22 are joined.

The substrate 24 should also be capable of being rolled, to supportconventional manufacturing processes, flexible so that the substrate 24may be bent or flexed in a desired configuration, and able to withstandthe heat of the liquid prongs 22 being deposited upon the prongattachment surface 25 of the substrate protuberances 23 without meltingor incurring deleterious effects until such prongs 22 freeze. Thesubstrate 24 should also be available in a variety of widths. Suitablesubstrates 24 capable of supporting protuberances 23, include knittedfabric, woven materials, nonwoven materials, rubber, vinyl, films,particularly kraft paper and preferably polyolefinic films. White kraftpaper having a basis weight of 0.08 kilograms per square meter (50pounds per 3,000 square feet) has been found suitable.

The base 26 is the generally planar portion of the prong 22 which isattached to the prong attachment surface 25 of the substrateprotuberances 23 of the substrate 24 and is contiguous with the proximalend of the shank 28 of the prong. As used herein, the term "base" refersto that portion of the prong 22 which is in direct contact with theprong attachment surface 25 of the substrate 24 and supports the shank28 of the prong 22. It is not necessary that a demarcation be apparentbetween the base 26 and the shank 28. It is only important that theshank 28 not separate from the base 26 and that the base 26 not separatefrom the prong attachment surface 25 during use. The base 26 crosssection should provide sufficient structural integrity, and hence area,for the desired peel and shear strengths of the fastening system 20,based on the density of the pattern of prongs 22 and length of theshanks 28 of the individual prongs 22 and further provide adequateadhesion to the prong attachment surface 25. If a longer shank 28 isutilized, the base 26 should generally be of greater cross sectionalarea providing sufficient adhesion to the prong attachment surface 25and adequate structural integrity.

The shape of the footprint of the base 26 on the prong attachmentsurface 25 will generally correspond to the area of the prong attachmentsurface 25. The footprint may be enlarged by increasing the area of theprong attachment surface 25 of the substrate protrusions 23, this willprovide greater structural integrity and thus a greater peel strength inthat direction. As used herein, the term "footprint" refers to theplanar contact area of the base 26 on the prong attachment surface 25 ofthe protruding areas 23 of the substrate 24. The aspect ratio of thesides of the footprint should not be too great, otherwise the prong 22may be unstable when subjected to forces parallel to the shorter side ofthe footprint. An aspect ratio of less than about 1.5:1 is preferred anda generally circular prong attachment surface 25 corresponding to acircular footprint is more preferred. However, altering the shape of thefootprint can result in the formation of a free formed prong having anazimuthal angle. Such prongs are described in greater detail in Procter& Gamble applications 4417, Ser. No. 07/719211, filed in the name ofThomas et al. on Jun. 21, 1991, now abandoned and U.S. Pat. No.5,180,534, issued Jan. 19, 1993, to Thomas et al. both hereinincorporated by reference.

For the embodiment described herein, a base 26 having a footprint ofgenerally circular shape placed upon a generally circular prongattachment surface 25 of a substrate protrusion 23 being approximately0.76 millimeters to 1.27 millimeters (0.030 to 0.050 inches) in diameteris suitable. If it is desired to make the fastening system 20 have agreater peel or shear strength in a particular direction, the crosssectional area of the prong attachment surface 25 and substrateprotrusion 23 and correspondingly the base 26 may be modified to amplifysuch direction, so that the strength and structural integrity relativeto the axis orthogonal to such direction increases. This modificationcauses the prongs 22 to be stronger when pulled in the amplifieddirection of the base 26.

The shank 28 is contiguous with the base 26 and projects outwardly fromthe base 26 and the prong attachment surface 25 of the substrateprotrusion 23. As used herein, the term "shank" refers to that portionof the prong 22 which is intermediate of and contiguous with the base 26and the engaging means 30. The shank 28 provides longitudinal spacing ofthe engaging means 30 from the prong attachment surface 25 of thesubstrate protrusions 23. As used herein, the term "longitudinal" meansin a direction having a vector component away from the prong attachmentsurface 25, which direction increases the perpendicular distance to theplane of the prong attachment surface 25 at the base-prong attachmentinterface of the prong 22, unless otherwise specified to be a directionhaving a vector component towards such plane of the prong attachmentsurface 25.

Associated with the shank 28 and base 26 of each prong 22 is an origin36. The "origin" of the shank 28 is the point which may be thought of asthe center of the base 26 and therefore the center of the prongattachment surface 25, and is typically within the footprint of the base26. The origin 36 is found by viewing the prong 22, from the side view.The "side view" is any direction radially towards the shank 28 and base26 which is also parallel to the plane of the prong attachment surface25 of the substrate 24. If the fastening system 20 is manufactured bythe process described and claimed below, it is preferred, but notnecessary, that the prong 22 be viewed in the machine and crossmachinedirections, relative to the travel of the substrate 24 through the nip70, when determining the origin 36.

The lateral distance between the remote edges of the base 26 footprintfor the particular side view under consideration is found, and thisdistance is bisected, yielding the midpoint of the base 26 for suchview. When bisecting the footprint of the base 26 for the particularside view under consideration, minor discontinuities (such as fillets orasperities incident to the attachment to substrate 24) are ignored. Thispoint is the origin 36 of the shank 28.

The shank 28 makes an angle α with the plane of the prong attachmentsurface 25, substrate protrusion 23 and the substrate 24. As usedherein, the term "plane of the prong attachment surface" refers to theflat, planar surface of the substrate protrusions at the base 26 of theprincipal prong 22 under consideration. The angle α is determined asfollows. The prong 22 is viewed in profile. The "profile view" of theprong 22 is one of two particular side views and found as follows. Theprong 22 is visually inspected from the side views such that thedirection having the maximum lateral projection 38 becomes apparent. The"lateral projection" is the distance taken laterally and parallel to theplane of the prong attachment surface 25 from the center of the base 26in such view, i.e. the origin 36 of the shank 28, to the projection ofthe furthest laterally remote point on the prong 22 visible in such viewwhen such point is longitudinally and perpendicularly projected downwardto the plane of the prong attachment surface 25.

It will be apparent to one skilled in the art that the maximum lateralprojection 38 is that projection from the origin 36 to the outerperiphery of the shank 28 or engaging means 30. The side view of theprong 22 which maximizes the lateral projection 38 is the profile viewof such prong 22. It will also be apparent to one skilled in the artthat if the fastening system 20 is produced by the process described andclaimed below, the maximum lateral projection 38 is generally orientedin the machine direction and, hence, the profile view is generallyoriented in the cross-machine direction. The side elevational view shownin FIG. 2 is one of the profile views of the prong 22 placed upon anemboss 19. It will be further apparent to one skilled in the art thatthere is another profile view, generally 180° opposite from the profileview shown (so that the maximum lateral projection 38 is orientedtowards the left of the viewer). Either of the two profile views isgenerally equally well suited for the procedures and usages describedhereinbelow.

The origin 36 of the shank 28 is found, as described above, with theprong 22 in the profile view. While still maintaining the prong 22 inthe profile view, an imaginary cutting plane 40--40, generally parallelto the plane of the prong attachment surface 25 and the substrate 24, isthen brought into tangency with the periphery of the prong 22 at thepoint or segment of the prong 22 having the greatest perpendiculardistance from the plane of the prong attachment surface 25. Thiscorresponds to the portion of the prong 22 having the highest elevation.The imaginary cutting plane 40--40 is then brought one-fourth of suchgreatest perpendicular distance closer to the prong attachment surfaceof highest elevation, so that the imaginary cutting plane 40--40intercepts the prong 22 at a longitudinal elevation three-fourths of theperpendicular distance from the plane of the prong attachment surface25.

The imaginary cutting plane 40--40 is then used to determine threepoints on the prong 22. The first point is that point where the cuttingplane intercepts the leading edge 42 of the prong 22 and is referred toas the 75% leading point 44. The "leading edge" is the apex of theperiphery of the shank 28 which longitudinally faces away from the planeof the prong attachment surface 25 and the substrate 24. The secondpoint is disposed about 180° through the center of the prong 22 and isthe point where the cutting plane 40--40 intercepts the trailing edge 46of the prong 22 and is referred to as the 75% trailing point 48. The"trailing edge" is the apex of the periphery of the shank 28 whichlongitudinally faces towards the prong attachment surface 25 and thesubstrate 24 and is generally oppositely disposed from the leading edge42. The straight line connecting these two points falls, of course,within the cutting plane 40--40 and is bisected to yield the midpoint 47of the imaginary cutting plane 40--40. A straight line is then drawnconnecting the midpoint 47 of the imaginary cutting plane 40--40 withthe origin 36 of the shank 28 at the base 26. The included angle α thisline defines, relative to the plane of the prong attachment surface 25,is the angle α of the shank 28.

Alternatively stated, the angle a which the shank 28 makes relative tothe plane of the prong attachment surface 25 is the 90° complement ofthat angle furthest from the perpendicular defined by the line, found inany side view, connecting the cutting plane midpoint 47 and the origin36. Hence, the smallest angle relative to the plane of the prongattachment surface 25 when this line is viewed in any direction radiallytowards the shank 28, and particularly the origin 36, which direction isgenerally parallel to the plane of the prong attachment surface 25 andorthogonal to the perpendicular is the angle α of the shank 28. It is tobe recognized that when the prong 22 is viewed approximately in themachine direction, or approximately 180° therefrom, the apparent angle αof the shank 28 will be about 90°. However, as discussed above, theangle α to be measured is that which deviates furthest from theperpendicular and, therefore, is generally that angle α determined whenthe prong 22 is viewed in profile, typically from about thecross-machine direction.

The angle α of the shank 28 may be generally perpendicular to the planeof the prong attachment surface 25, or is preferably oriented in anacute angular relation relative thereto to provide increased peelstrength in a particular direction, which direction is generallyparallel to the maximum longitudinal projection 38. However, the angle αof the shank 28 should not deviate excessively from the perpendicular,otherwise a fastening system 20 of more directionally specific shearstrength results. For the embodiment described herein, a shank 28 havingan angle a between about 45° and about 80°, preferably about 65°, workswell. If the angle of the shank 28 is less than about 80°, the shank 28is considered to be nonperpendicularly oriented relative to the plane ofthe prong attachment surface 25 (without regard to lateral orientation).

The imaginary cutting plane 40--40 and profile view can also be utilizedto determine the angles of the leading edge 42 and the trailing edge 46relative to the plane of the prong attachment surface 25. To determinethese angles, the 75% leading point 44 and 75% trailing point 48 arefound as described above. The base 26 leading point 50 is found asfollows. The line through the base 26 upon the prong attachment surface25 as viewed in profile is brought to intersect the leading edge 42 ofthe shank 28. This intersection is the "base leading point" 50. As notedabove, minor discontinuities in the shank 28 near the base 26, incidentto attachment to the prong attachment surface 25, are not consideredwhen determining the base leading point 50. The 75% leading edge 42point 44 is connected by a straight line to the base leading edge 42point 50. This straight line forms an included angle β_(L) relative tothe plane of the prong attachment surface 25 and opening in thedirection of the origin 36 and center of the shank 28. The angle β_(L)is referred to as the angle of the leading edge 42 or simply the leadingedge angle.

The base trailing point 52 is generally disposed 180° from the baseleading point 50, through the center of the base 26, and found asfollows. The line through the footprint of the base 26, andcorrespondingly the prong attachment surface 25, as viewed in profile isbrought to intersect the trailing edge 46 of the shank 28. Thisintersection is the "base trailing point." As noted above, minordiscontinuities in the shank 28 near the base 26, incident to attachmentto the prong attachment surface 25 is not considered when determiningthe base trailing point 52. As described above, the 75% trailing point48 is connected with the base trailing point 52 by a straight line. Thisstraight line forms an included angle β_(T) relative to the plane of theprong attachment surface 25 and opening in the direction of the origin36 and center of the shank 28. The included angle β_(T) is referred toas the angle of the trailing edge 46 or simply the trailing edge angle.

The leading edge 42 and trailing edge 46 included angles β_(L) and β_(T)define the parallelism of the sides of the shank 28. If the angles β_(L)and β_(T) of the leading and trailing edges 42 and 46 are notsupplementary to each other (do not add to an arithmetic sum of about180°) the sides of the shank 28 are said to be nonparallel. If the sidesof the shank 28 are nonparallel, the straight lines which define theangles β_(L) and β_(T) (connecting the base leading and trailing points50 and 52 with the 75% leading and trailing points 44 and 48respectively) intersect, either above or below the plane of the prongattachment surface 25. If the angles β_(L) and β_(T) of the leading andtrailing edges 42 and 46 are unequal and the lines defining such anglesintersect above the plane of the prong attachment surface 25(longitudinally outwardly of the base 26), the prong 22 will convergefrom the base 26 towards the distal end and engaging means 30. Only ifthe angles β_(L) and β_(T) of the leading and trailing edges 42 and 46have the same sense i.e., are oriented in the same direction, andsupplementary magnitudes are the angles β_(L) and β_(T) of the leadingand trailing edges 42 and 46 determined to be equal and the sides of theshank 28 to be parallel.

A shank 28 having a leading edge 42 which forms a leading edge angleβ_(L) with the prong attachment surface 25 of about 45°±30° is suitable.A trailing edge 46 which forms a trailing edge angle β_(T) with theprong attachment surface 25 of about 65°±30° is suitable. A shank 28having these angles β_(L) and β_(T) of the leading and trailing edges 42and 46 works well with the aforementioned spectrum of included angles αof the shank 28 to yield a tapered shank 28, advantageously orientedrelative to the prong attachment surface 25 to provide high shear andpeel strengths without requiring excessive prong material.

The foregoing measurements are easily made using a Model 100-00 115goniometer sold by Rame'-Hart, Inc. of Mountain Lakes, N.J. If moreprecise measurement is desired, it will be recognized by one skilled inthe art that determination of the profile view, origin 36, cutting plane40--40, leading angle β_(L), trailing angle β_(T), base points 50 and52, 75% points 44 and 48, and the angle α of the shank 28 can beadvantageously performed by making a photograph of the prong 22. A model1700 scanning electron microscope sold by Amray, Inc. of New Bedford,Mass. has been found to work well for this purpose. If necessary,several photographs may be taken to determine the maximum lateralprojection 38 and hence, either profile view.

The shank 28 should longitudinally project from the base 26 a distancesufficient to space the engaging means 30 from the protruding portions23 of the substrate 24 at an elevation which allows the engaging means30 to readily intercept or engage the strands of the receiving surface.A relatively longer shank 28 provides the advantage that it canpenetrate deeper into the receiving surface and thereby allow theengaging means 30 to intercept or engage a greater number of strands orfibers. Conversely, a relatively shorter shank 28 length provides theadvantage that a relatively stronger prong 22 results, but also providescorrespondingly less penetration into the receiving surface and maytherefore be unsuitable for receiving surfaces such as wool or looselystitched bonded materials which have less densely packed strands orfibers.

If a knitted or woven material receiving surface is utilized, arelatively shorter shank 28 having a longitudinal length from the prongattachment surface 25 to the point or segment of highest elevation ofabout 0.5 millimeters (0.020 inches), preferably at least about 0.7millimeters (0.028 inches), is suitable. If a high loft materialreceiving surface having a caliper greater than about 0.9 millimeters(0.035 inches) is utilized, a relatively longer shank 28 having agreater longitudinal dimension of at least about 1.2 millimeters (0.047inches), preferably at least about 2.0 millimeters (0.079 inches), ismore suitable. As the shank 28 length increases, and shear strengthcorrespondingly diminishes, the density of the protruding portions 23 ofthe substrate 24 and correspondingly of the prongs 22 of the fasteningsystem 20 may be increased to compensate for such loss of shearstrength.

At this point, it can readily be discerned by one of skill in the artthat a substrate protrusion 23 consisting of an embossed 19 or raised 21portion will provide additional height to the prong 22 allowing theprong 22 to penetrate deeper into the receiving means. Another advantageto an embossed 19 area of a substrate 24 is the prongs increased "skinfriendliness." Placing the prong on an embossed 19 area of the substrate24 allows the prong 22 to encapsulate or submerge within the embossed 19area when pressed against the skin. This encapsulation also allows theprongs 22 lock any fibers of a receiving surface by permitting the prongengaging means 30 opening to descend below the surface of the substrate24. This locking phenomenon does not prevent the receiving surface frombeing removed from the engaging means 30 but, increases the hook'sholding strength.

The substrate of the present invention having protuberances may also beused as a compressible substrate to form a skin friendly hook fasteningmaterial. Such a friendly hook fastening material and methods of makingsuch a hook fastening material are disclosed in U.S. patent applicationSer. No. 07/988,636, "Non-Abrasive Mechanical Fastening System AndProcess of Manufacture Therefore", filed Dec. 10, 1992, in the name ofDavid J. K. Goulait et al. and is incorporated herein by reference.

As described above, the longitudinal length of the shank 28 determinesthe longitudinal spacing of the engaging means 30 from the prongattachment surface 25. The "longitudinal spacing" is the leastperpendicular distance from the plane of the prong attachment surface 25to the periphery of the engaging means 30. For an engaging means 30 ofconstant geometry, the longitudinal spacing of the engaging means 30from the prong attachment surface 25 becomes greater with increasinglongitudinal shank 28 length. A longitudinal spacing of at least abouttwice the strand or fiber diameter of the intended receiving surface,and preferably about 10 times as great as such fiber or strand diameterprovides good interception or engagement and retention of such strandsor fibers by the engaging means 30 of the fastening system 20. For theembodiment described herein, a prong 20 having a longitudinal spacing ofabout 0.2 millimeters to about 0.8 millimeters (0.008 to 0.03 inches)works well.

The shape of the cross section of the shank 28 is not critical. Thus theshank 28 may be of any cross section desired, according to theaforementioned parameters relating to the cross section of the base 26.The "cross section" is the planar area of any part of the prong 22 takenperpendicular to the shank 28 or the engaging means 30. As noted above,the shank 28 is preferably tapered to decrease in cross section as thedistal end of the shank 28 and engaging means 30 of the prong 22 arelongitudinally and laterally approximated. This arrangement provides acorresponding decrease in the moment of inertia of the shank 28 andengaging means 30 resulting in a prong 22 of more nearly constant stresswhen separation forces are applied to the fastening system 20, andthereby diminishes the quantity of superfluous materials incorporatedinto the prong 22.

To maintain the desired geometry over a wide range of prong 22 sizes, agenerally uniform ratio of cross sectional areas can be utilized toscale the prongs 22. One ratio which generally controls the overalltaper of the prong 22 is the ratio of the area of the prong attachmentsurface 25 and the cross section of the base 26 to the area of the crosssection of the prong 22, at the highest elevation of the prong 22. Thephrase "highest elevation" refers to the that point or segment of theshank 28 or the engaging means 30 having the greatest perpendiculardistance from the plane of the prong attachment surface 25. Typically,prongs 22 having a base 26 cross sectional area to highest elevationcross sectional area ratio in the range of about 4:1 to about 9:1 workwell.

A generally circular shank 28 which tapers from a base 26 diameter, asdiscussed above, ranging from about 0.76 millimeters to about 1.27millimeters (0.030 to about 0.050 inches) to a highest elevationdiameter, of about 0.41 millimeters to about 0.51 millimeters (0.016 to0.020 inches) has been found suitable for the embodiment discussedherein. Recognizable by one skilled in the an is the fact that the areaof the base conforms to the area of the prong attachment surface 25.Specifically, a generally circular shaped prong attachment surface 25area cross section of about 0.46 millimeters (0.018 inches) diameter atthe highest elevation provides a cross sectional area at highestelevation of about 0.17 square millimeters (0.0003 square inches). Agenerally circular shaped prong attachment surface 25 and base 26 crosssection of about 1.0 millimeters (0.040 inches) provides a base 26 crosssectional area of about 0.81 square millimeters (0.0013 square inches).This structure results in a ratio of base 26 cross sectional area tohighest elevation cross sectional area of about 5:1, which is within theaforementioned range.

The engaging means 30 is joined to the shank 28, and preferably iscontiguous with the distal end of the shank 28. The engaging means 30projects radially away and outwardly from the periphery of shank 28, andmay further have a vector component which longitudinally projects, i.e.towards or away from the prong attachment surface 25. As used herein theterm "engaging means" refers to any protrusion lateral to the peripheryof shank 28 (other than minor asperities in the periphery of the shank28), which protrusion resists separation or removal from a receivingsurface. The term "periphery" means the outer surface of the prong 22.The term "radially" means from or towards the perpendicular to the prongattachment surface 25 or substrate 24, which perpendicular passesthrough the origin 36 which is generally centered within the footprintof the base 26.

Particularly, the lateral protrusion has a vector component parallel toand facing towards the plane of the prong attachment surface 25 and thesubstrate 24. It is to be recognized that the engaging means 30 andshank 28 may have both lateral and longitudinal vector components. It isnot important that a sharply defined terminus of the shank 28 distal endbe apparent, or that a demarcation between the shank 28 and engagingmeans 30 be discernible at all. It is only necessary that alongitudinally oriented face of the shank 28 periphery be interrupted sothat the engaging means 30 has a face with a vector component parallelto and facing the plane of the prong attachment surface 25 and thesubstrate 24.

The engaging means 30 may have a greater lateral projection 38 than theshank 28, or vice-versa, as desired. As illustrated in the figures, theengaging means 30 is preferably generally arcuate and may have areentrant curve. If the engaging means 30 has a reentrant curve, theengaging means 30 includes a segment which longitudinally approximatesthe prong attachment surface 25 or the substrate 24 at the base 26 or alocation laterally spaced from the base 26. This segment is laterallydirected towards the shank 28, although the segment need not be radiallydirected towards the origin 36.

The engaging means 30 of each prong 22 of the fastening system 20 maylaterally extend substantially in the same direction, if a relativelyunidirectionally oriented peel strength is desired, or may be randomlyoriented to provide substantially isotropic peel strengths in anylateral direction. The engaging means 30 may be hook-shaped tines whichproject substantially from one side of the shank 28, defining agenerally convex outline, and penetrate the opening of the receivingsurface to intercept the strands or fibers of the receiving surface atthe inner radius of curvature 54 of the engaging means 30. Theinterference between the engaging means 30 and strands or fibers of thereceiving surface prevents release of the fastening system 20 from thereceiving surface until the peel strength or shear strength of thefastening system 20 is exceeded. The engaging means 30 should notradially project too far in the lateral direction, otherwise theengaging means 30 may not penetrate the opening of the receivingsurface. The cross section of the engaging means 30 should be sized topenetrate the openings of the receiving surface.

The cross sectional area and geometry of the engaging means 30 are notcritical, so long as the engaging means 30 has structural integritywhich provides sufficient shear and bending strengths to accommodate thedesired peel and shear strengths of a fastening system 20 having anarray of prongs 22 of a given density. For the embodiment describedherein, a hook-shaped tine engaging means 30 having a maximum lateralprojection 38 from the center of the base 26 to the remote lateralperiphery of about 0.79 millimeters to about 0.90 millimeters (0.03 to0.04 inches) is suitable.

The array of substrate protrusions 23 and correspondingly the prongs 22may be of any pattern and density as desired, to achieve the peel andshear strengths required for the particular application of the fasteningsystem 20. Generally as the array density increases, peel strength andshear strength proportionately increase in a linear fashion. Theindividual prongs 22 should not be so closely spaced as to interferewith and prevent the engaging means 30 of the adjacent prongs 22 fromintercepting strands or fibers of the receiving surface. If the prongs22 are too closely spaced, compacting or matting of the receivingsurface strands or fibers may occur, occluding the openings between thestrands or fibers. Conversely, the prongs 22 should not be so distantlyspaced as to require an excessive area to provide a fastening system 20of adequate shear and peel strengths.

It is advantageous to dispose the substrate protrusions 23 in rows, sothat each prong 22 is generally equally spaced from the adjacent prong22. Generally, the machine direction and cross-machine directionsubstrate protrusions 23 should be equally spaced from the adjacentmachine direction and cross-machine direction substrate protrusions 23,to provide a generally uniform stress field throughout the fasteningsystem 20 and the receiving surface when separation forces are appliedto the fastening system 20 and the receiving surface.

As used herein the term "pitch" refers to the distance, measured eitherin the machine direction or cross-machine direction, between the centersof the substrate protrusions 23 and correspondingly the prongattachments surfaces 25 or the footprints of the bases 26 of prongs 22in adjacent rows. Typically a fastening system 20 having an array ofprongs 22 with a pitch ranging from about 1.02 millimeters to about 5.08millimeters (0.04 to 0.20 inches) in both directions is suitable, with apitch of about 2.03 millimeters (0.08 inches) being preferred. Adjacentcross-machine direction rows are preferably offset approximatelyone-half pitch in the cross-machine direction to double the distance inthe machine direction between the adjacent cross-machine direction rows.

The substrate protrusions 23 and correspondingly the prongs 22 may bethought of as disposed in a matrix on a one square centimeter gridhaving an array of substrate protrusions 23 and correspondingly prongs22 with about 2 to about 10 rows of prongs 22 per centimeter (5 to 25rows per inch) in both the machine and cross-machine directions,preferably about 5 rows of prongs 22 per centimeter (13 rows per inch)in each direction. This grid will result in a fastening system 20 havingabout 4 to about 100 prongs 22 per square centimeter (25 to 625 prongsper square inch) of substrate 24.

The fastening system's 20 prongs 22 may be made of any thermallysensitive material which is stable and shape retaining when solid, butnot so brittle that failure occurs when the fastening system 20 issubjected to separation forces. As used herein, "thermally sensitive"means a material which gradually changes from the solid state to theliquid state upon the application of heat. Failure is considered to haveoccurred when the prong 22 has fractured or can no longer sustain areaction in the presence of and when subjected to separation forces.Preferably the material has an elastic tensile modulus, measuredaccording to ASTM Standard D-638, of about 24,600,000 to about31,600,000 kilograms per square meter (35,00 to 45,000 pounds per squareinch).

Further, the prong material should have a melting point low enough toprovide for easy processing and a relatively high viscosity to provide atacky and tough consistency at temperatures near the material meltingpoint, so that the shanks 28 may be stretched and the engaging means 30easily formed according to the method of manufacture recited below. Itis also important that the prongs 22 be viscoelastic, to allow for morevariation in the parameters affecting prong 22 structure, andparticularly the geometry of the engaging means 30. Material having acomplex viscosity ranging from about 20 to about 100 Pascal seconds atthe temperature of application to the substrate protrusions 23 issuitable.

The viscosity may be measured with a Rheometrics Model 800 MechanicalSpectrometer using the dynamic operating mode at a 10 Hertz samplingfrequency and 10% material strain. A disk and plate type geometry ispreferred, particularly with a disk having a radius of about 12.5millimeters and a gap of about 1.0 millimeters between the disk andplate.

The prongs 22 are preferentially comprised of a thermoplastic material.The term "thermoplastic" refers to uncrosslinked polymers of a thermallysensitive material which flows under the application of heat orpressure. Hot melt adhesive thermoplastics are particularly well suitedto manufacture the fastening system 20 of the present invention,particularly in accordance with the process described and claimed below.As used herein the phrase "hot melt adhesive" refers to thermoplasticcompounds, normally solid at room temperature, which become fluid atelevated temperatures and which are applied in the molten state.Examples of hot melt adhesives may be found in the "Handbook OfAdhesives," Second Edition by Irving Skeist, published in 1977 by VanNostrand Reinhold Company, 135 West 50th Street, New York, N.Y., 10020,which is incorporated herein by reference. Polyester and polyamide hotmelt adhesives are particularly suitable and preferred. As used herein,the terms "polyester" and "polyamide" mean chains having repeating esterand amide units respectively.

If a polyester hot melt adhesive is selected, an adhesive having acomplex viscosity of about 23±2 Pascal seconds at about 194° C. has beenfound to work well. If a polyamide hot melt adhesive is selected, anadhesive having a complex viscosity of about 90±10 Pascal seconds atabout 204° C. has been found to work well. A polyester hot melt adhesivemarketed by the Bostik Company of Middleton, Mass. as No. 7199 has beenfound to work well. A polyamide hot melt adhesive marketed by the HenkelCompany of Kankakee, Ill. under the tradename Macromelt 6300 has beenfound to work well.

In a second embodiment of the fastening system 20', illustrated by FIG.4, the engaging means 30' may be generally semispherically (mushroom)shaped. The term "semispherical" means a generally round shape,protruding in multiple directions and is inclusive of hemispheres andspheres, but not limited to regular shapes. This geometry, particularlythe generally spherically shaped engaging means 30' structure, providesthe advantage that less disturbance to the strands of the receivingsurface typically occurs when the engaging means 30' is removed from thereceiving surface. This causes less visible damage to the receivingsurface, allowing it to be reused a greater number of times. If thesemispherically shaped engaging means 30' is selected, the shank 28' ispreferably more nearly orthogonal to the plane of the prong attachmentsurface 25, to allow easier penetration into the openings of thereceiving surface and to reduce damage to the receiving surface as theengaging means 30' is released from the receiving surface. A shank 28'having an angle α' of about 70° to about 90° is suitable.

To provide a prong 22' of the proper proportions and having a generallysemispherical engaging means 30', the engaging means 30' should radiallyprotrude from the circumference of the shank 28' a lateral distancesufficient to intercept the strands of the receiving surface, but notprotrude so far that the mass of the engaging means 30' is unable to berigidly supported by the shank 28' or the shank 28' is otherwiseunstable. As the angle α of the shank 28' decreases, i.e. deviatesfurther from the perpendicular, the mass of the engaging means 30'relative to the shank 28' structural integrity and cross sectional areabecomes more critical.

A tapered shank 28', having the base 26' to highest elevation crosssectional area and diameter ratios described above, and an angle α'ofthe shank 28' of about 80° works well. It is to be recognized thehighest elevation measurements are to be taken from the highestelevation of the shank 28' and not from the engaging means 30'.

For an embodiment, as illustrated in FIG. 4, which does not have asmooth transition from the shank 28' to the engaging means 30', and forwhich the demarcation between the shank 28' and engaging means 30' iseasily determined, the imaginary cutting plane 40'--40' is three-fourthsof the perpendicular distance from the plane of the prong attachmentsurface 25 to the plane tangent to the point of the engaging means 30'which is longitudinally closest to the plane of the prong attachmentsurface 25. The cutting plane 40'--40' is then used to determine theangle α of the shank 28', the leading edge angle β_(L) ' and trailingedge angle β_(T) ' as described above.

The engaging means 30' should radially project, in each lateraldirection, from the periphery of the distal end 29' of the shank 28' atleast about 25 percent of the diameter of the distal end 29' of theshank 28', and preferably at least about 38 percent of such diameter.Alternatively stated, if the diameter of the distal end 29' of shank 28'is normalized to 1.0, the diameter of the engaging means 30' should beat least 1.5, and preferably at least 1.75 times the diameter of thedistal end 29' of the shank 28'. Furthermore, the diameter of the base26' should be about 2.0 times the diameter of the distal end 29' of theshank 28'. The shank 28' height should be about 1.5 to about 2 times thediameter of the distal end 29' of the shank 28', to properlylongitudinally space the engaging means 30' from the prong attachmentsurface 25. The longitudinal dimension of the engaging means 30' mayrange from about 0.5 to about 1.5 times the diameter of the distal end29' of the shank 28'.

The fastening system 20' of FIG. 4 is made by heating the engaging means30 and distal end of the fastening system 20 of FIG. 2 to at least themelting point. This is accomplished by bringing the engaging means 30and distal ends of the prongs 22 to a heat source longitudinallydirected toward the plane of the substrate so that the base 26' and theproximal end of the shank 28' are not heated to at least the meltingpoint. A suitable method is to bring the highest elevation of the prongto within about 3.3 millimeters to about 10.1 millimeters (0.1 to 0.4inches) of a heat source, such as a hot wire heated to about 440° C.

The leading edge angle β_(L) ' and trailing edge angle β_(T) ' of theprong 22' will be similar to that of the corresponding hook-shag tinestyle engaging means prong 22, from which the semispherically shapedengaging means style prong 22' was formed. This occurs because the angleα or of the shank 28' and leading edge and trailing edge angles β_(L) 'and β_(T) ' do not substantially change as the engaging means 30 of FIG.2 is heated and melted to flow into the engaging means 30' of FIG. 4.

For the aforementioned Milliken 970026 receiving surface, the engagingmeans 30' of FIG. 4 should preferably have a lateral and longitudinaldimension of about 0.029 millimeters to about 0.032 millimeters (0.001inches), and be disposed on a shank 28' having a base 26' diameter ofabout 0.30 millimeters to about 0.045 millimeters (0.012 to 0.002inches) and a diameter at the distal end 29' of about 0.016 millimetersto about 0.020 millimeters (0.0006 to 0.0007 inches). The distal end 29'of the shank 28' should be disposed between about 0.44 millimeters andabout 0.50 millimeters (0.017 inches to 0.020 inches) above the plane ofthe prong attachment surface 25, and the engaging means 30' should havea lateral projection 38' of about 0.56 millimeters to about 0.70millimeters (0.022 to 0.028 inches), preferably about 0.64 millimeters(0.025 inches).

PROCESS OF MANUFACTURE

The fastening system 20 according to the present invention may bemanufactured using a process similar to gravure printing. Gravureprinting is well known in the art as illustrated by U.S. Pat. No.4,643,130 issued Feb. 17, 1988, to Sheath et al. and incorporated hereinby reference to illustrate the state of the art similar to the presentinvention. Another reference which produces similar prongs is U.S. Pat.No. 5,116,563 issued May 26, 1992 to Thomas et al. and incorporatedherein by reference.

Referring now to FIG. 5 the substrate 24 containing protrusions 23 ispassed through the nip 70 formed between two rolls, a smooth print roll72 and a backing roll 4. The rolls 72 and 74 have substantially mutuallyparallel centerlines disposed generally parallel to the plane of theprong attachment surface 25 and the substrate 24. The rolls 72 and 74are rotated about the respective centerlines and have generally equalsurface velocities, in both magnitude and direction, at the nip point70. If desired, one or both the smooth print roll 72 and the backingroll 74 may be driven by an external motive force (not shown). Analternating current electric motor having an output of about 1,500 wattsprovides adequate motive force. By rotating, the rolls 72 and 74 actuatethe substrate 24 causing the prong material to adhere to the prongattachment surface 25 of the substrate protrusions 23 of the substrate24.

The smooth print roll 72 should be able to accommodate the temperatureof the material of prongs 22 in the liquid state and providesubstantially uniform pitch between the prongs 22 in both the machineand cross-machine directions. It can be gleaned, that by varying thecross-sectional area of the prong attachment surface 25 on the substrateprotrusions 23 various base diameters 26 and shank heights will beproduced.

The smooth print roll 72, provides for the depositing means to depositthe prongs 22 on the prong attachment surface 25. The pattern of thesubstrate protrusions 23 on the substrate 24 provides the desired array.The phrase "depositing means" refers to anything which transfers liquidprong material from a bulk quantity to the prong attachment surface 25.The term "deposit" means to transfer prong material from the bulk formand dose such material onto the prong attachment surface 25.

The cross sectional area of the prong attachment surface 25 andcorrespondingly the substrate protuberances 23 generally correspondswith the shape of the footprint of the base 26 of the prong 22. Thecross section of the prong attachment surface 25 should be approximatelyequal to the desired cross section of the base 26. The depth of theprong material which is deposited upon the smooth print roll 72, inpart, determines the longitudinal length of the prong 22, specificallythe perpendicular distance from the base 26 to the point or segment ofhighest elevation.

For the embodiment described herein, the depth of the prong materialspread upon the smooth print roll 72 should be between about 50 andabout 70 percent of the diameter of the prong attachment surface 25.

The smooth print roll 72 and backing roll 74 should be coincident withthe line connecting the centerlines of the rolls permitting thesubstrate protrusions 23 to collect prong material accumulated upon thesmooth print roll 72 to be deposited upon the prong attachment surface25 of the substrate 24.

The backing roll 74 should be somewhat softer and more compliant thanthe smooth print roll 72 to provide cushioning of the prong material asit is deposited on the prong attachment surface 25 from the smooth printroll 72. A backing roll 74 having a rubber coating with a Shore Adurometer hardness of about 40 to about 60 is suitable.

The smooth print roll 72 temperature is not critical, however, the printroll 72 should be heated to prevent solidification of the prongs 22during transfer from the source through the deposition on to the prongattachment surface 25. Generally a print roll 72 surface temperaturenear the source material temperature is desired. A smooth print roll 72temperature of about 197° C. has been found to work well.

It is to be recognized that a chill roll may be necessary if thesubstrate 24 is adversely affected by the heat transferred from theprong material. If a chill roll is desired, it may be incorporated intothe backing roll 74 using means well known to one skilled in the art.This arrangement is often necessary if a polypropylene, polyethylene orother polyolefinic substrates are used.

The material used to form the individual prongs 22 must be kept in asource which provides for the proper temperature to apply the prongs 22to the prong attachment surface 25. Typically, a temperature slightlyabove the melting point of the material is desired. The material isconsidered to be at or above the "melting point" if the material ispartially or wholly in the liquid state. If the source of the prongmaterial is kept at too high a temperature, the prong material may notbe viscous enough and may produce engaging means 30 which laterallyconnect to the prongs 22 adjacent in the machine direction. If thematerial temperature is very hot, the prong 22 will flow into a small,somewhat semispherically shaped puddle and an engaging means 30 will notbe formed. Conversely, if the source temperature is too low, the prongmaterial may not transfer from the source 80 to the smooth print roll 72or, subsequently, may not properly transfer from the smooth print roll72 to the prong attachment surface 25 of the substrate 24. The source ofthe material should also impart a generally uniform cross-machinedirection temperature profile to the material, be in communication withthe means for depositing the adhesive material onto the prong attachmentsurface 25 of the substrate 24 and easily be replenished or restocked asthe prong material becomes depleted.

A suitable source is a trough 80, substantially coextensive of thatportion of the cross-machine dimension of the smooth print roll 72 andadjacent thereto. The trough 80 has a closed end bottom, an outboardside and ends. The top may be open or closed as desired. The inboardside of the trough 80 is open, allowing the liquid material therein tofreely contact and communicate with the circumference of the smoothprint roll 72.

The source is externally heated by known means (not shown) to maintainthe prong material in a liquid state and at the proper temperature. Thepreferred temperature is above the melting point but below that at whicha significant loss of viscoelasticity occurs. If desired, the liquidmaterial inside the trough 80 may be mixed or recirculated to promotehomogeneity and an even temperature distribution.

Juxtaposed with the bottom of the trough 80 is a doctor blade 82 whichcontrols the amount of prong material applied to the smooth print roll72. The doctor blade 82 and trough 80 are held stationary as the smoothprint roll 72 is rotated, allowing the doctor blade 82 to wipe thecircumference of the roll 72 and scrape any prong material which isapplied at a depth of greater then the depth intended to be depositedupon the smooth print roll 72 and allows such material to be recycled.This arrangement allows prong material to be deposited from the smoothapplicator roll 72 on to the prong attachment surface 25 in the desiredarray, according to the geometry of the substrate protuberances 23. Asseen in FIG. 5, the doctor blade 82 is preferentially disposed in thehorizontal plane, particularly the horizontal apex of the smooth printroll 72, which apex is upstream of the nip point 70.

After being deposited onto the prong attachment surface 25, the prongs22 are severed from the smooth applicator roll 72 by a means forsevering 78 the prongs 22 into the engaging means 30 of the fasteningsystem 20 and a moil. As used herein the term "moil" refers to anymaterial severed from the prong 22 and which does not form part of thefastening system 20.

The severing means 78 should be adjustable to accommodate various sizesof prongs 22 and lateral projections 38 of engaging means 30 and alsoprovide uniformity throughout the cross-machine direction of the array.The term "severing means" refers to anything which longitudinallyseparates the moil from the fastening system 20. The term "sever" refersto the act of dividing the moil from the fastening system 20 asdescribed above. The severing means 78 should also be clean and shouldnot rust, oxidize or impart corrodents and contaminates (such as moilmaterial) to the prongs 22. A suitable severing means is a wire 78disposed generally parallel to the axis of the rolls 72 and 74 andspaced from the substrate protrusions 23 a distance which is somewhatgreater than the perpendicular distance from the highest elevation ofthe solidified prong 22 to the substrate protuberances 23.

Preferably the wire 78 is electrically heated to prevent build-up of themolten prong material on the severing means 78, accommodate any coolingof the prongs 22 which occurs between the time the prong material leavesthe heated source and severing occurs and to promote lateral stretchingof the engaging means 30. The heating of the severing means 78 shouldalso provide for uniform temperature distribution in the cross-machinedirection, so that an array of prongs 22 having substantially uniformgeometry is produced.

Generally, as the prong material temperature increases a relativelycooler hot wire 78 temperature severing means can be accommodated. Also,as the speed of the substrate 24 is decreased, less frequent cooling ofthe hot wire 78 occurs as each prong 22 and moil are severed, making arelatively lower wattage hot wire 78 more feasible at the sametemperatures. It should be recognized that as the temperature of the hotwire 78 is increased a prong 22 having a generally shorter shank 28length will result. Conversely, the shank 28 length and lateral lengthof the engaging means 30 will be increased in inverse proportion as thetemperature of the hot wire 78 is decreased. It is not necessary thatthe severing means 78 actually contact the prong 22 for severing tooccur. The prong 22 may be severed by the radiant heat emitted from thesevering means 78.

For the embodiment described herein a round cross sectionnickel-chromium wire 78, having a diameter of about 0.51 millimeters(0.02 inches) heated to a temperature of about 343° C. to about 416° C.has been found suitable. It will be apparent that a knife, laser cuttingor other severing means 78 may be substituted for the hot wire 78described above.

It is important that the severing means 78 be disposed at a positionwhich allows stretching of the prong material to occur prior to theprong 22 being severed from the moil. If the severing means 78 isdisposed too far from the plane of the prong attachment surface 25, theprong material will pass underneath the severing means 78 and not beintercepted by it, forming a very long engaging means 30 which will notbe properly spaced from the prong attachment surface 25 or adjacentprongs 22. Conversely, if the severing means 78 is disposed too close tothe plane of the prong attachment surface 25, the severing means 78 willtruncate the shank 28 and an engaging means 30 may not be formed.

A hot wire severing means 78 disposed approximately 14 millimeters to 22millimeters (0.56 to 0.88 inches), preferably about 18 millimeters (0.72inches) in the machine direction from the nip point 70, approximately4.8 millimeters to 7.9 millimeters (0.19 to 0.31 inches), preferablyabout 6.4 millimeters (0.25 inches) radially outward from the backingroll 74 and approximately 1.5 millimeters to approximately 4.8millimeters (0.06 to 0.19 inches), preferably about 3.3 millimeters(0.13 inches) radially outwardly from the smooth print roll 72 isadequately positioned for the process of manufacture disclosed herein.

In operation, the substrate 24, with protrusions 23 having a prongattachment surface 25, is transported in a first direction relative tothe depositing means 76. More particularly, the substrate 24 istransported through the nip 70, preferentially drawn by a take-up roll(not shown). This provides a clean area of substrate 24, withprotrusions 23, for continuous deposition of prongs 22 upon the prongattachment surface 25 of the substrate 24 and removes the portions ofthe substrate 24 having prongs 22 deposited thereon. The directiongenerally parallel to the principal direction of transport of thesubstrate 24 as it passes through the nip 70 is referred to as the"machine direction." The machine direction, as indicated by the arrow 75of FIG. 5, is generally orthogonal the centerline of the smooth printroll 72 and backing roll 74. The direction generally orthogonal to themachine direction and parallel to the plane of the substrate 24 isreferred to as the "cross-machine direction."

The substrate 24 may be drawn through the nip 70 at a speedapproximately 2% to approximately 10% greater than the surface speed ofthe rolls 72 and 74. This is done to minimize bunching or puckering ofthe substrate 24 near the means for severing 78 the prongs 22 from themeans for depositing the prong material on the prong attachment surface25. The substrate 24 is transported through the nip 70 in the firstdirection at about 3 to about 31 meters per minute (10 to 100 feet perminute).

The angle α of the shank 28 can be influenced by the rate of transportof the substrate 24 past the nip 70. If prongs 22 having a shank angle amore nearly perpendicular to the prong attachment surface 25 is desired,a slower rate of transport of the substrate 24 in the first direction isselected. Conversely, if the rate of transport is increased, the angle αof the shank 28 decreases and an engaging means 30 have a greaterlateral projection 38 will result.

If desired, the substrate 24 may be inclined at an angle Ε,approximately 35° to approximately 55°, preferably about 45°, from theplane of the nip 70 towards the backing roll 74 to utilize theviscoelastic nature of the prong material and properly orient theengaging means 30 in the lateral direction, as well as longitudinaldirection. This arrangement also provides a greater force to pull theprong 22 away from the print roll 72. The angle Ε from the plane of thenip 70 should be increased as a lesser angle α of the shank 28 isdesired. Also, increasing the angle Ε of deviation from the plane of thenip 70 has a weak, but positive effect to produce engaging means 30having a greater lateral projection 38.

After depositing prong material from the smooth applicator roll 72 ontothe prong attachment surface 25, the rolls 72 and 74 continue rotation,in the directions indicated by the arrows 75 of FIG. 5. This results ina period of relative displacement between the transported substrate 24and the smooth print roll 72 during which period (prior to severing) theprong material bridges the prong attachment surface 25 and print roll72. As relative displacement continues, the prong material is stretcheduntil severing occurs and the prong 22 is separated from the smoothapplicator roll 72. As used herein the term "stretch" means to increasein linear dimension, at least a portion of which increase becomessubstantially permanent for the life of the fastening system 20.

As discussed above, it is also necessary to sever the individual prongs22 from the smooth applicator roll 72 as pan of the process which formsthe engaging means 30. When severed, a prong 22 is longitudinallydivided into two pans, a distal end and engaging means 30 which remainwith the fastening system 20 and a moil (not shown) which remains withthe smooth applicator roll 72 and may be recycled, as desired. After theprongs 22 are severed from the moil, the fastening system 20 is allowedto freeze prior to contact of the prongs 22 with other objects. Aftersolidification of the prongs 22, the substrate 24 may be wound into aroll for storage as desired.

A nonlimiting illustration of the process shows the prong material to bedisposed in the trough 80 and heated by means commonly known to oneskilled in the art, to a temperature somewhat above the melting point.If a polyester resin hot melt adhesive is selected, a materialtemperature of approximately 177°-193° C., preferably about 186° C. hasbeen found suitable. If a polyamide resin is selected, a materialtemperature of approximately 193°-213° C., preferably about 200° C. hasbeen found suitable. A one sided bleached kraft paper substrate 24having protrusions 23 about 0.008 to about 0.15 millimeters (0.003 to0.006 inches) in thickness works well with hot melt adhesive prongs 22.The prongs 22 are joined to the prong attachment surface 25 on thebleached side of the kraft paper substrate 24.

For the illustrated operation described herein, a substrate withprotrusions 23 having an array of 8 rows of protuberances 23 percentimeter (20 rows per inch), yielding 64 protuberances 23 per squarecentimeter (400 per square inch), is suitable. This grid density may beadvantageously used with a smooth application roll 72 having a diameterof about 16 centimeters (6.3 inches), in diameter. A backing roll 74having a diameter of about 15.2 centimeters (6.0 inches) and verticallyregistered has been found to work well with the aforementioned smoothapplication roll 72. The rate of transport of the substrate 24 is about3.0 meters per minute (10 feet per minute).

A nickel-chromium hot wire 78 having a diameter of about 0.5 millimeters(0.02 inches) disposed approximately 18 millimeters (0.72 inches) fromthe nip point 70 in the machine direction, approximately 0.3 millimeters(0.13 inches) radially outwardly from the print roll 72 andapproximately 6.4 millimeters (0.25 inches) radially outwardly from thebacking roll 74 is heated to a temperature of about 382° C. Thefastening system 20 produced by this operation is substantially similarto that illustrated by FIG. 1, which fastening system 20 may beadvantageously incorporated into the illustrative article of usediscussed below.

Without being bound by any particular theory, it is believed that thegeometry of the engaging means 30 is governed by the differentialcooling of the prong 22. The trailing edge 46 of the prong 22 isshielded and insulated from the heat originating from the severing means78. Conversely, the leading edge 42 is directly exposed to the heat ofthe severing means 78, which causes the leading edge 42 to cool moreslowly than the rate at which the trailing edge 46 cools. The resultingdifferential cooling rate causes elongation of the leading edge 42 andcontraction of the trailing edge 46, relative to each other. As thisdifferential cooling rate is increased, a relatively longer engagingmeans 30 is formed.

Referring to FIG. 6, if a fastening system 20" of more nearly isotropicpeel strength is desired, such a fastening system 20" may be formed bymodifying the fastening system 20 of FIG. 1 through a second stagedifferential temperature process. As illustrated in FIG. 6, thefastening system 20 of FIG. 1 is further processed to provide shanks 28"with engaging means 30" which radially extend from the shanks 28" invarious lateral directions of a generally random orientation. The phrase"random orientation" means having lateral projections and profile viewswhich significantly deviate in direction from those of the nearby prongs22".

This structure is accomplished by establishing a temperaturedifferential between the profile surfaces or leading surfaces 42 and thetrailing surfaces 46 of the prongs 22 of the fastening system 20 ofFIG. 1. Such temperature differential may be enhanced by radiation orpreferably convection.

Upon attaining a temperature differential of the leading surface 42" orthe profile surfaces relative to the trailing surface 46', the engagingmeans 30" will substantially change or even reverse the orientation oflateral projection, providing a prong 22" which is oriented in adirection other than that which occurred when initially cooled orfrozen. The differential temperature may be established by any sourceknown to one skilled in the art, such as a heated wire or metal element,and preferably an air gun 84, disposed above the prongs 22" and capableof providing a directed temperature differential to the fastening system20".

It is desired that the directed temperature differential source directan air current towards the fastening system 20" within about ±90° of thefirst direction of the substrate 24" travel, which is the machinedirection. As used herein, the phrase "±90° of the first direction"means a direction having a vector component generally perpendicular toor generally counter to the first direction of travel of the substrate24" and is inclusive of the direction generally opposite the firstdirection of travel.

If the directed temperature differential source 84 is disposed at anangle of about 180° relative to the first direction of travel of thesubstrate 24", the source 84 is directed towards the leading surfaces42" of the prongs 22" of the fastening system 20", and generallyopposite the machine direction of the process described and claimedherein. Directing the temperature differential of source 84 directlytowards the leading surface 42" of a prong 22" will result in thelateral projection 38" of the engaging means 30" rotating, to change theorientation of the lateral projection about 180°. Prongs 22" disposedsomewhat to the side, i.e. in the cross-machine direction of thedirected temperature differential source 84 will not have the engagingmeans 30" rotated about 180°, but instead engaging means 30" more nearlyrotated about 90°. Thus, it is apparent that a directed temperaturedifferential source 84 oriented in the cross-machine direction willprovide a fastening system 20" having prongs 22" with various lateralorientations in the cross-machine direction according to the prong 22"position relative to the temperature differential source 84.

An air gun 84 discharging air at a temperature of about 88° C. at adistance of about 46 centimeters (18 inches) from the substrate 24" is asuitable differential temperature source. A 133-348 series heat gun soldby the Dayton Electric Manufacturing Company of Chicago, Ill. orientedat about 45° relative to the plane of the substrate 24" and disposedabout 46 centimeters (18 inches) from the prongs produces a fasteningsystem 20" pattern substantially similar to that shown in FIG. 6. Itwill be apparent to one skilled in the art that one or more hot wiresdisposed above the prongs 22" and oriented in the machine direction willproduce a fastening system 20" having cross machine directionallyoriented engaging means 30" in a regular, somewhat striped pattern.

Without being bound by any theory, it is believed that the change inorientation of the engaging means 30" occurs due to the cooling of theprofile surfaces or the leading surface 42" of the prong 22" relative tothe trailing surface 46", which may occur if the temperature of thedischarged air from the directed temperature source differential source84 is less than the temperature of the periphery of such profilesurfaces or leading surface 42". The temperature differential resultingfrom the cooling causes contraction of the portion of the prong 22"towards which the temperature differential source 84 is directed. Thiscontraction may result in a change in the orientation of the engagingmeans 30" and lateral projection 38", due to the differential cooling ofthe leading surface 42" relative to the trailing surface 46". Withoutbeing bound by further theory, it is believed that relief of residualstresses which occur during cooling may influence the change inorientation of the lateral projection 38".

It will be further to apparent to one skilled in the art that othervariations are feasible. For example, a prong 22 having an engagingmeans 30 protruding in more than one direction may be formed or freeformed prongs 22 may be produced by commonly known methods other thanthe methods herein described. If desired, only one roll may be utilizedin the manufacturing process, providing, the prong attachment surface 25contacts at least about 180" of the periphery of such roll.

Referring to FIG. 7, if desired, and without being limited by theory,the process for creating embossed areas 19 on a substrate 24' can beincorporated into the prong printing process, thereby embossing thesubstrate 24' and printing the prongs 22' in a single continuousprocedure. The substrate 24' is passed through the nip 69' formedbetween two rolls, a rubber impression roll 73' and a steel embossingroll 74'. The rubber impression roll 73' and the steel embossing roll74' should be coincident with the line connecting the centerlines of therolls. The rubber impression roll 73' provides elastic cushioningenabling the embossing roll 74' to emboss the substrate 24' with raisedthree dimensional impressions or embosses 19 and creating a prongattachment surface 25. The embossing roll 74' contains on its surfacenumerous raised knobs that when pressed against the substrate 24 and therubber impression roll 73 as it passes through the nip 69', stretchesthe substrate producing an array of embosses 19 corresponding to thepattern of knobs contained on the embossing roll 74'. The now embossedsubstrate 25' follows the embossing roll 74' through another nip 70'formed between two rolls, the embossing roll 74' and the smoothapplicator roll 72' where prongs are placed upon the prong attachmentsurface 25 of the embossed substrate 25'. Subsequent modifications andchanges in the process and the profile and capabilities of the prongsmay be made as described above.

ILLUSTRATIVE ARTICLE OF USE

An illustrative and nonlimiting example of the usage of the fasteningsystem 20 of the present invention in an article of manufacture followsand is illustrated in FIG. 8. Mechanical fastening systems have beenadvantageously used in disposable absorbent articles as disclosed inU.S. Pat. 4,846,815, issued Jul. 11, 1989 to Scripps, which isincorporated herein by reference for the purpose of showing a diaper 110structure and the advantageous utilization of mechanical fasteningsystems 20 in such diaper 120 structures.

It is known, for example, that mechanical fastening systems 120 are lesseasily contaminated by oils and powders than are adhesive tape fasteningsystems and, further, may be easily reused. All of these featuresprovide advantages when applied to a disposable diaper 110 intended foruse on an infant. Also, a refastenable fastening system provides theadvantage that the infant may be checked to see if soiling of thedisposable diaper 110 has occurred during the wearing period.

Referring to FIG. 8, there is shown a disposable diaper 110 intended tobe worn about the lower torso by an infant. As used herein, the term"disposable absorbent article" refers to a garment generally worn byinfants or incontinent persons and which is drawn between the legs,fastened about the waist of the wearer and intended to be discardedafter a single use and not to be laundered or restored. A "disposablediaper" is a particular disposable article intended and scaled to beworn by an infant.

A preferred diaper 110 comprises a liquid pervious topsheet 112, aliquid impervious backsheet 116, and an absorbent core 118 intermediateto the topsheet 112 and backsheet 116. The topsheet 112 and backsheet116 are at least partially peripherally joined to ensure the core 118 isheld in position. The diaper 110 elements may be assembled in a varietyof configurations well known to one skilled in the art, with a preferredconfiguration being generally described in U.S. Pat. No. 3,860,003issued Jan. 14, 1975 to Buell, which patent is incorporated herein byreference for the purpose of disclosing a particularly preferred diaper110 configuration.

The topsheet 112 and backsheet 116 of the diaper 110 are generallycoextensive and at least partially peripherally joined together as notedabove. Joining of the topsheet 112 and backsheet 116 may be accomplishedby a hot-melt adhesive, such as Eastobond A3 manufactured by the EastmanChemical Products Company of Kingsport, Tenn. The absorbent core 118 haslength and width dimensions generally less than that of the topsheet 112and backsheet 116. The core 118 is interposed between the topsheet 112and backsheet 116 in fixed relationship.

The diaper 110 periphery comprises oppositely disposed first and secondends 122 and 124. The diaper 110 has a first waist portion 142 and asecond waist portion 144 extending respectively from the first end 122and second end 124 of the diaper 110 periphery towards the lateralcenterline of the diaper 110 a distance of about one-fifth to aboutone-third the length of the diaper 110. The waist portions 142 and 144comprise those portions of the diaper 110 which, when worn, encircle thewaist of the wearer and are generally at the highest elevation of thediaper 110 when the wearer is in the standing position. The crotch 146of the diaper 110 is that portion of the disposed between the first andsecond waist portions 142 and 144 and which, when worn is positionedbetween the legs of the wearer.

The absorbent "core" is any means for absorbing and retaining liquidbody exudates. The absorbent core 118 is generally compressible,conformable, and nonirritating to the skin of the wearer. A preferredcore 118 has first and second opposed faces and may, if desired, befurther encased by tissue layers. One opposed face of the core 118 isoriented towards the topsheet 112 and the other opposed face is orientedtowards the backsheet 116.

The absorbent core 118 is superimposed on the backsheet 116 andpreferably joined thereto by any means well known in the art such asadhesive bonding. In a particularly preferred embodiment, adhesivebonding is accomplished by longitudinal adhesive bands which join thecore 118 to the backsheet 116. The backsheet 116 is impervious toliquids and prevents liquids absorbed by and contained in the absorbentcore 118 from wetting undergarments, clothing, bedding and any otherobjects which contact the diaper 110. As used herein, the term"backsheet" refers to any barrier disposed outwardly of the core 118 asthe diaper 110 is worn and which contains absorbed liquids within thediaper 110. Preferably, the backsheet 116 is a polyolefinic film ofabout 0.012 to about 0.051 mm (0.0005-0.002 inches) in thickness. Apolyethylene film is particularly preferred, with a suitable film beingmanufactured by the Monsanto Company of St. Louis, Mo. as film No. 8020.If desired, the backsheet 116 may be embossed or matte finished toprovide a more clothlike appearance or be provided with passages topermit escape of vapors.

The topsheet 112 is compliant, tactily pleasing and nonirritating to thewearer's skin. The topsheet 112 prevents contact of the absorbent core118 and liquids therein with the skin of the wearer. The topsheet 112 isliquid pervious, permitting liquids to readily penetrate therethrough.As used herein, the term "topsheet" refers to any liquid pervious facingwhich contacts the skin of the wearer while the diaper 110 is being wornand prevents the core 118 from contacting the skin of the wearer. Thetopsheet 112 may be made of woven or nonwoven materials. A preferredtopsheet 112 is carded and thermally bonded by means to those skilled inthe nonwoven fabrics art. A particularly preferred topsheet 112 has aweight of about 18 to about 25 grams per square meter, a minimum drytensile strength of about 400 grams per centimeter in the machinedirection and a wet tensile strength of at least about 550 grams percentimeter in the cross-machine direction.

The diaper 110 is provided with a fastening system 120 and receivingsurface 153 for maintaining the first waist portion 142 and second waistportion 144 in an overlapping configuration when the diaper 110 is worn,so that the diaper 110 is secured to the wearer. Thus, the diaper 110 isfitted to the wearer and a side closure is formed when the fasteningsystem 120 is secured to the receiving surface 153.

The fastening system 120 should resist the separation forces which occurduring the wearing period. The term "separation forces" refers to forcesacting on the fastening system 120 and receiving surface 153 which tendto cause separation, release or removal of the fastening system 120 fromthe receiving surface 153. Separation forces include both shear and peelforces. The term "shear force" refers to distributive forces actinggenerally tangential to the receiving surface 153 and which may bethought of as being generally parallel to the plane of the substrate ofthe fastening system 120. The term "peel forces" refers to distributiveforces acting in the generally longitudinal direction, and perpendicularto the plane of the receiving surface 153 and fastening system 120substrates.

Shear forces are measured by tensile pulling of the fastening system 120and receiving surface 153 in opposite directions generally parallel tothe planes of the respective substrates. The method used to determinethe resistance of a fastening system 120 and receiving surface 153 toshear forces is more fully set forth in U.S. Pat. 4,699,622 issued Oct.13, 1987, to Toussant et at., which patent is incorporated herein byreference for the purpose of describing the measurement of shear forces.

Peel forces are measured by tensile pulling of the fastening system 120from the receiving surface 153 at an included angle of about 135°. Themethod used to determine the resistance of a fastening system 120 andreceiving surface 153 to peel forces is more fully set forth in U.S.Pat. No. 4,846,815, issued Jul. 11, 1989, to Scripps, which isincorporated herein by reference for the purpose of describing themeasurement of peel forces.

Separation forces are typically generated by movements of the wearer orby the wearer trying to unfasten the diaper 110. Generally, an infantshould not be able to unfasten or remove a diaper 110 the infant iswearing, nor should the diaper 110 come unfastened in the presence ofordinary separation forces which occur during normal wearing. However,an adult should be able to remove the diaper 110 to change it whensoiled or check to see if soiling has occurred. Generally, the fasteningsystem 120 and receiving surface 153 should resist a peel force of atleast 200 grams, preferably at least about 500 grams, and morepreferably, at least about 700 grams. Furthermore, the fastening system120 and receiving surface 153 should resist a shear force of at least500 grams, preferably at least about 750 grams, and more preferably atleast about 1,000 grams.

The receiving surface 153 may be disposed in a first position anywhereon the diaper 110, so long as the receiving surface 153 engages thefastening means to maintain the first and second waist portions 144 inan overlapping configuration. For example, the receiving surface 153 maybe disposed on the outside surface of the second waist portion 144, onthe inside surface of the first waist portion 142, or any other positionon the diaper 110 on which it is disposed so as to engage with thefastening system 120. The receiving surface 153 may be integral, adiscrete element joined to the diaper 110, or a single piece of materialthat is neither divided or discontinuous with an element of the diaper110, such as the topsheet 112 or backsheet 116.

While the receiving surface 153 may assume various sizes and shapes, thereceiving surface 153 preferably comprises one or more integral patchespositioned across the outside surface of the second waist portion 144 toallow for maximum fit adjustment at the waist of the wearer. Asillustrated in FIG. 8, the receiving surface 153 is preferably anelongate rectangularly shaped integral member secured to the outersurface of the second waist portion 144.

A suitable receiving surface 153 is stitch bonded, nonwoven fabric orany other type of fiber or loop material well known in the art. Thereceiving surface 153 may be manufactured from a variety of materialswhich provide fiber elements, and preferably loops capable of beingintercepted and retained by the engaging means. Suitable materialsinclude nylon, polyester, polypropylene and combinations of theforegoing. A suitable receiving surface 153 comprises a number of fiberloops projecting from a woven and is commercially available asScotchmate brand nylon woven loop No. FJ3401, sold by the MinnesotaMining and Manufacturing Company of St. Paul, Minn. Another suitablereceiving surface 153 comprises a tricot having a plurality of nylonfilament loops projecting from a nylon backing and is commerciallyavailable form Gilford Mills of Greensboro, N.C. and designated anddesignated Gilford No. 16110. A particularly preferred receiving surfaceis stitchbonded loop material sold by the Milliken Company ofSpartanburg, S.C. under Number 970026.

The fastening system 120 is intended to engage the complementaryreceiving surface 153 to provide a secure fit for the diaper 110. Thefastening system 120 may comprise any of the well known configurationsutilized for achieving a side closure on a disposable diaper 110. Thefastening system 120 substrate is joined to the diaper 110 in spacedrelationship from the receiving means 153. As shown on FIG. 8, thefastening system 120 is preferably disposed on both the first and secondlongitudinal sides of the diaper 110. A preferred configuration for thefastening system 120 minimizes any potential contact between the prongsof the fastening system 120 and the skin of the wearer. A preferredfastening system 120 disposition is a Y-shaped tape arrangement,described in detail in U.S. Pat. No. 3,848,594 issued Nov. 19, 1974 toBuell. An alternatively preferred fastening system 120 arrangement isdescribed in detail in U.S. Pat. No. 4,699,622 issued Oct. 13, 1987 toToussant et al., both of which patents are incorporated herein byreference for the purpose of illustrating various placements of thefastening system 120 on the disposable diaper 110.

The fastening system 120 of FIG. 8 has a manufacturer's end 156 and anoppositely disposed user's end 158. The manufacturer's end 156 is joinedto the diaper 110, preferably in juxtaposition with the first waistportion 142. The user's end 158 is the free end and is secured to thereceiving surface 153 when the diaper 110 is secured to the wearer.

After the diaper 110 is fitted about the waist of the wearer, the user'send 158 of the fastening system 120 is releasably secured to thereceiving surface 153, and preferably positioned on the second waistportion 144, thereby causing the diaper 110 to encircle the waist of thewearer. The diaper 110 has now effected a side closure. The prongs (notshown) extend from the fastening system 120 of the user's end 158 sothat the prong engaging means intercept the strands of the receivingsurface 153.

A fastening system 120 and complementary receiving surface 153 whichprovides a resistance to peel forces in excess of 700 grams and aresistance to shear forces in excess of 1,000 grams may be constructedas follows according to the specific parameters of the fastening system120 set forth in the aforementioned "Process of Manufacture." Thecomplementary receiving surface 153 used in conjunction with thefastening system 120 is the aforementioned Milliken Company No. 970026stitchbonded loop fabric.

The fastening system 120 is at least about 2.54 centimeters (1 inch) inwidth and may be of any length which provides a convenient user's end158, with a length of at least about 3.5 centimeters (1.4 inches) beingpreferred. The array of the prongs of fastening system 120 comprises amatrix having about 26 prongs per square centimeter (169 prongs persquare inch). The prongs are preferentially oriented in substantiallythe same direction and face the user's end 158 of the fastening tape.

In use, the diaper 110 is applied to the wearer by positioning the firstwaist portion 142 around the wearer's back and drawing the remainder ofthe diaper 110 between the legs of the wearer so that the second waistportion 144 is disposed across the front of the wearer. The user's ends158 of the fastening system 120 are then secured to the receivingsurface 153 on the outside surface of the second waist portion 144 toform a side closure.

What is claimed is:
 1. A process for making a fastening systemcomprising one or more free formed prongs, the process comprising thesteps of:(a) providing a molten thermally sensitive material; (b)providing a substrate having one or more protrusions; (c) depositingdiscrete amounts of said molten thermally sensitive material on one ormore of said protrusions on (of) said substrate; (d) stretching aportion of said discrete amounts of said molten thermally sensitivematerial in a direction having a vector component parallel to the planeof said substrate so as to form a prong on each said protrusion havingsaid molten thermally sensitive material deposited thereon; and (e)solidifying said molten thermally sensitive material of said prong, saidprong having a base, a shank, and an engaging means.
 2. The processaccording to claim 1 wherein said step of depositing discrete amounts ofsaid molten thermally sensitive material on said protrusionscomprises:(a) providing a first roll adapted to rotate about itscenterline, which centerline is disposed generally parallel to the planeof said substrate; (b) providing a smooth applicator surface on saidfirst roll; (c) disposing said molten thermally sensitive material onthe smooth surface of said first roll; and (d) rotating said first rolluntil said smooth surface containing said molten thermally sensitivematerial contacts said protrusions of said substrate.
 3. The processaccording to claim 2 further comprising:(a) providing a doctor blade injuxtapositional relationship with the periphery of said first roll; and(b) scraping excess material from said first roll with said doctor bladeas said first roll is rotated.
 4. The process according to claim 3further comprising:(a) providing a backing roll having a centerlinedisposed generally parallel to said centerline of said first roll; b)juxtaposing said first roll and said backing roll to form a niptherebetween; and (c) rotating said first roll and said backing roll ata substantially equal surface velocity at said nip, wherein saidsubstrate is transported through said nip in a first direction.
 5. Theprocess according to claim 4 wherein said substrate is transported at asubstantially uniform velocity.
 6. The process according to claim 1wherein said step of stretching said discrete amounts of moltenthermally sensitive material forms a prong and a moil and wherein theprocess additionally comprises the step of severing said moil from saidprong, and wherein said step of severing said moil comprises:(a)disposing a generally stationary means for severing said moilsubstantially across said substrate; and (b) intercepting said moil withsaid stationary means.
 7. The process according to claim 6 furthercomprising heating said means for severing said material.
 8. The processaccording to claim 7 wherein said severing means is heated to atemperature of at least the melting point of said stretched material. 9.The process according to claim 4 further comprising directing an aircurrent toward said discrete amounts of said molten thermally sensitivematerial in a second direction, said second direction being within about±90° of said first direction.
 10. The process according to claim 1further comprising establishing a temperature differential across saiddeposition of material.
 11. A process comprising the steps of:(a)providing a thermally sensitive material; (b) heating said thermallysensitive material to at least the melting point to provide a moltenthermally sensitive material; (c) providing a substrate; (d)transporting said substrate in a first direction; (e) embossing saidsubstrate to form one or more protrusions; (f depositing discreteamounts of said molten thermally sensitive material on one or more ofsaid protrusions on said substrate; (g) stretching a portion of saiddiscrete amounts of said molten thermally sensitive material in adirection having a vector component parallel to the plane of saidsubstrate so as to form a prong and a moil; (h) severing said moil fromsaid stretched molten thermally sensitive to leave said prong; and (i)solidifying said molten thermally sensitive material of said prong, saidprong having a base, a shank and an engaging means.
 12. The processaccording to claim 11 wherein said step of embossing said substratecomprises:(a) providing a rubber impression roll adapted to rotate aboutits centerline, which centerline is disposed generally parallel to theplane of said substrate and generally perpendicular to the firstdirection of transport; (b) providing a pattern roll adapted to rotateabout its centerline, which centerline is disposed generally parallel tothe plane of said substrate and generally perpendicular to the firstdirection of transport and wherein said pattern roll having raised knobsthereon; (c) rotating said pattern roll and said impression roll; (d)passing said substrate between said rubber impression roll and saidpattern roll and; (d) embossing said substrate by pressing said knobs ofsaid pattern roll against said substrate and said rubber impressionroll.
 13. The process according to claim 11 wherein said step ofdepositing said material on substrate comprises:(a) providing a firstroll adapted to rotate about its centerline, which centerline isdisposed generally parallel to the plane of substrate and generallyperpendicular to the first direction of transport; (b) providing asmooth applicator surface on said first roll; (c) disposing said moltenthermally sensitive material on the surface of said first roll; and (d)rotating said first roll until said smooth surface containing saidmaterial contacts said protrusions said substrate.
 14. The processaccording to claim 13 further comprising:(a) providing a doctor blade injuxtapositional relationship with the periphery of said first roll; and(b) scraping excess material from said first roll with said doctor bladeas said first roll is rotated.
 15. The process according to claim 11wherein said step of severing said moil comprises:(a) disposing agenerally stationary means for severing said moil substantially acrosssaid substrate; and (b) intercepting said moil with said means forsevering as said prong and said moil are transported by substrate. 16.The process according to claim 15 further comprising heating said meansfor severing said moil.
 17. The process according to claim 16 whereinsaid severing means is heated to a temperature of at least the meltingpoint of said stretched material.
 18. The process according to claim 11further comprising directing an air current towards said depositions ofmaterial in a second direction, said second direction being within about±90° of said first direction.
 19. The process according to claim 11further comprising establishing a temperature differential across saiddeposition of material.